Moldable uncured nonwoven composite and molded cured composite

ABSTRACT

A process for forming a moldable, uncured nonwoven composite containing forming a outermost nonwoven layer, forming a structural nonwoven layer, needling the structural nonwoven layer and the outermost nonwoven layer together from both the outer surface of the outermost nonwoven layer and the second surface of the structural nonwoven layer, applying an uncured, water-based thermosetting resin having a cure temperature of at least about 160° C. to the second surface of the structural nonwoven layer, and at least partially drying the uncured, wet nonwoven composite. Heat and pressure may be applied to form the moldable, uncured composite. A moldable, uncured nonwoven composite and a molded, cured nonwoven composite are also disclosed.

TECHNICAL FIELD OF THE INVENTION

The invention provides a moldable uncured nonwoven composite and amolded cured composite having good physical properties.

BACKGROUND

There are a number of products in various industries, includingautomotive, office and home furnishings, construction, and others; thatrequire materials having a z-direction thickness to provide bothstructural strength as well as thermal, sound insulation, aesthetic,and/or other performance features. In many of these applications it isalso required that the material be thermoformable to a specified shapeand rigidity. In the automotive industry these products often are usedfor shielding applications such as noise and thermal barriers inautomotive hood liners, underbody shields, firewall barriers, and trunkliners.

Composite materials used in automotive applications like packageshelves, door panels or headliners are often produced via cold pressingstructural nonwoven composite layers bound by a thermoplastic binderfiber to a decorative layer. For this, the composite layer used assubstrate bound by thermoplastic binder is heated by means of infraredradiation to a temperature between 180° C. and 200° C., placed in a coldmolding press together with a decorative layer, and cold pressed withthe decorative layer. The composite layer can comprise by way of examplepolypropylene or polyester core-sheath binder fibers, and use naturalfibers, glass or carbon fibers as the reinforcing fibers.

A disadvantage of these purely thermoplastic systems is that the weightper unit area of the composite substrate tends to be high in order toachieve the mechanical properties (modulus of elasticity and tensilemodulus) required. In addition, the composite may have dimensionalstability issues when the operating temperature exceeds the softeningpoint of the thermoplastic binder.

As an alternative to this, it is possible to use composite layers boundby a thermosetting resin system, for example bound by an epoxy resin.Here, a moldable prepreg is produced and then molded via hot pressing ina heated mold.

It is the objective of this invention to provide a process which issimple to carry out for producing structural nonwoven compositematerials with an A-surface face layer in one-step without the need foran adhesive or a separate lamination step. In addition, the inventionuses a combination of thermoplastic binder fiber and a thermosettingresin to improve the mechanical properties of the composite and thedimensional stability at elevated temperatures. In one embodiment,thermoplastic binder fibers with grafted functional groups are used toimprove the bond strength within the fiber network and improves themechanical properties.

BRIEF SUMMARY OF THE INVENTION

A process for forming a moldable, uncured nonwoven composite containingforming a outermost nonwoven layer, forming a structural nonwoven layer,placing the structural nonwoven layer and the outermost nonwoven layertogether such that the inner surface of the outermost nonwoven layer isadjacent the first surface of the structural nonwoven layer, needlingthe structural nonwoven layer and the outermost nonwoven layer togetherfrom both the outer surface of the outermost nonwoven layer and thesecond surface of the structural nonwoven layer, applying an uncured,water-based thermosetting resin having a cure temperature of at leastabout 160° C. to the second surface of the structural nonwoven layer,and at least partially drying the uncured, wet nonwoven composite.

The outermost nonwoven layer has an outer surface and an inner surfaceand the outermost nonwoven layer contains a plurality of first fiberswhich have a melting temperature greater than about 130° C. Thestructural nonwoven layer has a first surface, a second surface, and aninner plane located at the mid-plane between the first and secondsurface. The structural nonwoven layer contains a plurality of binderfibers and a plurality of reinforcing fibers. The needling causes aportion of the first fibers from the outermost nonwoven layer to migrateinto the structural nonwoven layer and causes a portion of thestructural fibers and the binder fibers from the structural nonwovenlayer to migrate into the outermost nonwoven layer. Applying theuncured, water-based thermosetting resin partially impregnates thenonwoven layers forming an uncured, wet nonwoven composite and at least90% by weight of the water-based thermosetting resin is located in thestructural nonwoven layer. When at least partially drying the uncured,wet nonwoven composite, the temperature at the inner plane of thestructural nonwoven layer is less than about 160° C. forming anmoldable, uncured nonwoven composite. Heat and pressure may be added tothe moldable, uncured nonwoven composite to form a molded curedcomposite.

A moldable, uncured nonwoven composite containing an outermost nonwovenlayer and a structural nonwoven layer. The outermost nonwoven layer hasan outer surface and an inner surface, where the outer surface of theoutermost nonwoven layer forms the first side of the moldable, uncurednonwoven composite. The outermost nonwoven layer comprises a pluralityof first fibers. The structural nonwoven layer has a first surface and asecond surface, where the first surface of the structural nonwoven layeris on the inner surface of the outermost nonwoven layer. The structuralnonwoven layer comprises a plurality of reinforcing fibers, a pluralityof binder fibers, and an uncured, water-based thermosetting resin havinga cure temperature of at least about 160° C. The outermost nonwovenlayer and structural nonwoven layer are needled together through theouter surface of the outermost nonwoven layer and the second surface ofthe structural nonwoven layer such that the structural nonwoven layerfurther comprises a plurality of first fibers from the outermostnonwoven layer and the outermost nonwoven layer further contains aplurality of structural fibers and binder fibers from the structuralnonwoven layer. At least 90% by weight of the water-based thermosettingresin of the moldable, uncured nonwoven composite is located in thestructural nonwoven layer.

A molded, cured nonwoven composite containing an outermost nonwovenlayer and a structural nonwoven layer. The outermost nonwoven layer hasan outer surface and an inner surface, wherein the outer surface of theoutermost nonwoven layer forms the first side of the moldable, uncurednonwoven composite and where the outermost nonwoven layer comprises aplurality of first fibers. The structural nonwoven layer has a firstsurface and a second surface, where the first surface of the structuralnonwoven layer is on the inner surface of the outermost nonwoven layerand the structural nonwoven layer comprises a plurality of reinforcingfibers, binder material, and a cured, water-based thermosetting resin.The outermost nonwoven layer and structural nonwoven layer are needledtogether through the outer surface of the outermost nonwoven layer andthe second surface of the structural nonwoven layer such that thestructural nonwoven layer further contains a plurality of first fibersfrom the outermost nonwoven layer and the outermost nonwoven layerfurther contains a plurality of structural fibers and binder fibers fromthe structural nonwoven layer. At least 90% by weight of the cured,water-based thermosetting resin of the molded, cured nonwoven compositeis located in the structural nonwoven layer. At least a portion of thereinforcing fibers are bonded to other reinforcing fibers through thebinder material and cured thermoset resin.

BRIEF DESCRIPTION OF THE FIGURES

An embodiment of the present invention will now be described by way ofexample, with reference to the accompanying drawings.

FIG. 1 illustrates schematically a cross-section of one embodiment ofthe moldable, uncured nonwoven composite.

FIG. 2 illustrates schematically a cross-section of an enlarged sectionof the moldable, uncured nonwoven composite of FIG. 1.

FIG. 3 illustrates schematically a cross-section of one embodiment ofthe moldable, uncured nonwoven composite.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown one embodiment of a moldable,uncured nonwoven composite 10. The moldable, uncured nonwoven composite10 contains a structural nonwoven layer 100 having a first side 100 a, asecond side 100 b, and an inner plane 100 c located at the mid-planebetween the first side 100 a and the second side 100 b. The structuralnonwoven layer 100 is a unitary material where the inner plane 100 c isnot a distinct plane or an adhesive connecting two zones together, theinner plane 100 c is simply a reference plane. Once the moldable,uncured nonwoven composite 10 is molded under heat and pressure, itbecomes the molded, cured composite.

In one embodiment, the thickness of the structural nonwoven layer 100 isbetween about 2 mm and 10 mm, more preferably between about 3 mm and 6mm. The thickness is defined as the distance between the first side 100a and the second sided 100 b of the structural nonwoven layer 100. Inone embodiment, the a real weight of the moldable, uncured nonwovencomposite 10 is between about 500 and 1000 g/m², more preferably betweenabout 500 and 800 g/m².

The process to form a moldable, uncured nonwoven composite 10 beginswith forming the structural nonwoven layer comprising a plurality ofreinforcing fibers 200 and binder fibers 300. The structural nonwovenlayer 100 is formed by the steps of blending, carding, and needlepunching the plurality of reinforcing fibers 200 and binder fibers 300.The reinforcing fibers 200 and binder fibers 300 may be located withinthe structural nonwoven layer in a generally uniform way or may bestratified meaning that the concentration of a particular fiber ishigher on the first side 100 a, second side 100 b, and/or inner plane100 c.

The structural nonwoven layer comprises a plurality of reinforcingfibers 200. The reinforcement fibers 200 may be staple or continuous.Some examples of suitable reinforcement fibers include glass fibers,aramid fibers, and highly oriented polypropylene fibers, bast fibers,polyester fibers, and carbon fibers.

The reinforcement fibers also provide volume to the structural nonwovenlayer 100. Additional examples of reinforcing fibers 200 would includefibers with high denier per filament (one denier per filament orlarger), high crimp fibers, hollow-fill fibers, and the like. Thesefibers provide mass and volume to the material. Some examples ofreinforcement fibers include polyester, polypropylene, and cotton, aswell as other low cost fibers. Preferably, the bulking fibers have adenier greater than about 6 denier. In another embodiment, the bulkingfibers have a denier greater than about 15 denier. The bulking fibersare preferably staple fibers. In one embodiment, the bulking fibers donot a circular cross section, but are fibers having a higher surfacearea, including but not limited to, segmented pie, 4DG, winged fibers,tri-lobal etc.

In one preferred embodiment, the reinforcement fibers comprise a naturalfiber. In one preferred embodiment, the reinforcement fibers comprise afiber selected from the group consisting of a bast fiber, a kenaf fiber,a fiberglass fiber, and mixtures thereof.

In one embodiment, the reinforcement fibers 200 may include fibers madefrom highly oriented polymers, such as gel-spun ultrahigh molecularweight polyethylene fibers (e.g., SPECTRA™ fibers from HoneywellAdvanced Fibers of Morristown, N.J. and DYNEEMA™ fibers from DSM HighPerformance Fibers Co. of the Netherlands), melt-spun polyethylenefibers (e.g., CERTRAN™ fibers from Celanese Fibers of Charlotte, N.C.),melt-spun nylon fibers (e.g., high tenacity type nylon 6,6 fibers fromInvista of Wichita, Kans.), melt-spun polyester fibers (e.g., hightenacity type polyethylene terephthalate fibers from Invista of Wichita,Kans.), and sintered polyethylene fibers (e.g., TENSYLON™ fibers fromITS of Charlotte, N.C.). Suitable reinforcement fibers also includethose made from rigid-rod polymers, such as lyotropic rigid-rodpolymers, heterocyclic rigid-rod polymers, and thermotropicliquid-crystalline polymers. Suitable reinforcement fibers 145 made fromlyotropic rigid-rod polymers include aramid fibers, such aspoly(p-phenyleneterephthalamide) fibers (e.g., KEVLAR™ fibers fromDuPont of Wilmington, Del. and TWARON™ fibers from Teijin of Japan) andfibers made from a 1:1 copolyterephthalamide of3,4′-diaminodiphenylether and p-phenylenediamine (e.g., TECHNORA™ fibersfrom Teijin of Japan). Suitable reinforcement fibers 145 made fromheterocyclic rigid-rod polymers, such as p-phenylene heterocyclics,include poly(p-phenylene-2,6-benzobisoxazole) fibers (PBO fibers) (e.g.,ZYLON™ fibers from Toyobo of Japan),poly(p-phenylene-2,6-benzobisthiazole) fibers (PBZT fibers), andpoly[2,6-diimidazo[4,5-b:4′,5′-e]pyridinylene-1,4-(2,5-dihydroxy)phenylen-e]fibers (PIPD fibers) (e.g., M5® fibers from DuPont of Wilmington, Del.).Suitable reinforcement fibers made from thermotropic liquid-crystallinepolymers include poly(6-hydroxy-2-napthoic acid-co-4-hydroxybenzoicacid) fibers (e.g., VECTRAN™ fibers from Celanese of Charlotte, N.C.).Suitable reinforcement fibers also include boron fibers, silicon carbidefibers, alumina fibers, glass fibers, and carbon fibers, such as thosemade from the high temperature pyrolysis of rayon, polyacrylonitrile(e.g., OPF™ fibers from Dow of Midland, Mich.), and mesomorphichydrocarbon tar (e.g., THORNEL™ fibers from Cytec of Greenville, S.C.).In another exemplary embodiment, the reinforcement fibers 200 may beselected from alkali resistant fibers such as e.g., polyvinyl alcohol(PVA) fibers, polypropylene fibers, polyethylene fibers, etc. In stillanother exemplary embodiment, reinforcement fibers 200 having an alkaliresistant coating may be used such as e.g., PVC coated glass fibers.

The structural nonwoven layer 100 also contains binder fibers 300. Thebinder fibers are fibers that form an adhesion or bond with the otherfibers. In one embodiment, the binder preferably are fibers that areheat activated. Examples of heat activated binder fibers are fibers thatcan melt at lower temperatures, such as low melt fibers, bi-componentfibers, such as side-by-side or core and sheath fibers with a lowersheath melting temperature, and the like.

In one embodiment, the binder fibers are bi-component fibers containingat least 2 components (they may contain 3 or more). In one embodiment,the bi-component fibers awe a core/sheath fiber meaning the fiberscontain a core comprising a core polymer and a sheath comprising asheath polymer. The core polymer has a higher melting temperature thanthe sheath polymer. In one embodiment, the core polymer has a meltingtemperature of at least about 180° C. and the sheath polymer has amelting temperature of less than about 180° C. In another embodiment,the core polymer has a melting temperature of at least about 180° C. andthe sheath polymer has a melting temperature of less than about 160° C.Preferably, the core/sheath fibers have a core polymer of polyester anda sheath polymer of a different polyester such that the core and sheathpolymers meet the melting temperature limitations.

The binder fibers are preferably staple fibers. In one embodiment, aftermolding under heat and pressure, the binder fibers are still discernablefibers with the sheath and or core at least partially intact. In anotherembodiment, the core of the core/sheath fibers remains intact but thesheath of the core/sheath fibers lose their fiber shape and form acoating on surrounding material. In another embodiment, binder fibersalmost completely lose their fiber shape and form a coating onsurrounding materials (when consolidated).

In one embodiment, a majority of the reinforcement fibers 200 areoriented such that the fibers form an angle with the inner plane 100 cof between about 0 and 25 degrees. In another embodiment, thereinforcement fibers 200 preferably are oriented generally in thez-direction (the z-direction is defined as the direction perpendicularto the inner plane 100 c. The z-orientation of the reinforcement fibers200 allows for increased thickness of the first zone 100. In thisembodiment, preferably a majority of the third fibers 130 have atangential angle of between about 25 and 90 degrees to the normal ofmidpoint plane between the first side 100 a and the inner plane 100 c.This means that if a tangent was drawn on the reinforcement fibers 200at the inner plane 100 c, the angle formed would be between about 90degrees and 25 degrees.

As the structural nonwoven layer is formed (before the introduction ofthe uncured, water-based thermosetting resin), the % by weight ratios ofreinforcement fibers to binder fibers is between about 50:50 to 90:10,more preferably between about 60:40 to 70:30. As the structural nonwovenlayer is formed (before the introduction of the uncured, water-basedthermosetting resin), the structural nonwoven layer preferably comprisesbetween about 10 and 50% by weight of binder fibers, more preferablybetween about 30 and 40%. As the structural nonwoven layer is formed(before the introduction of the uncured, water-based thermosettingresin), the structural nonwoven layer preferably comprises between about50 and 95% by weight of reinforcing fibers, more preferably betweenabout 60 and 60.

After the structural nonwoven layer 100 is formed, it is at leastpartially impregnated with an uncured, water-based thermosetting resin.The resin has a cure temperature of at least about 130° C., morepreferably about 160° C.

In one embodiment, suitable resins are commercially available forexample as aqueous dispersions of a polycarboxylic acid and/orstyrene-acrylic polymer modified with a polycarboxylic acid and a polyolas crosslinking component, such as ACRODUR™ from BASF Company,Ludwigshafen, Germany. Preferred grades include styrene-acrylic polymerACRODUR™ DS 3515 characterized by a solids content of about 50 weightpercent, a pH of about 3.5 and a viscosity of about 150-300 mPa·s;ACRODUR™ DS 3530 characterized by solids content of about 50 weightpercent, a pH of about 3.5 and a viscosity of about 150-300 mPas;ACRODUR™ DS 3558 characterized by a solids content of about 50 weightpercent, a pH of about 3.5 and a viscosity of about 300-1500 mPa·s; andACRODUR™ 950L characterized by a solids content of about 50 weightpercent, a pH of about 3.5 and a viscosity of about 900-2500 mPa·s. Inthe preferred embodiment, additives like surfactants, pigments,activated carbon and biocides can be added to the resin bath beforeimpregnating the structural nonwoven.

Aqueous resins are preferred over solvent based resin systems forenvironmental reasons and higher costs associated with solvent handlingand recovery.

The process for preparing the composite article may include a step ofimpregnating the structural nonwoven with the flowable polymer. Forexample, a mat of natural fibers and binder fibers may be impregnated bythe polymer or polymer solution. Preferably the natural fibers (e.g.,the mat of natural fibers includes a sufficient amount of open spaces,and the polymer solution includes a sufficient amount of water so thatthe polymer solution can flow into the open spaces (e.g. to form animpregnated mat or prepreg).

The process for preparing the composite article may include a step ofpartially drying the impregnated structural nonwoven (e.g. theimpregnated mat) to form partially dried impregnated prepreg. Drying theimpregnated prepreg may reduce the water concentration of theimpregnated fibers, partially cure the polymer, or both. The partiallydried impregnated prepreg preferably is sufficiently dried to reduce thewater concentration and/or partially cure the polymer so that it can behandled as a solid, so that the polymer does not flow out of the fibers,or both.

In one embodiment, the core fibers, binder fibers (and binder materialin the cured composite), and resin all comprise polyester. Monomaterialcompositions (material comprising the same polymer type) tend toeliminate chemical compatibility/bonding issues. In addition,constructions using the same material type can be more easily recycledand reused at end of life.

In one embodiment, the reinforcing fibers are cellulosic fibers,preferably bast fibers. As polysaccharides, these fibers have hydroxylgroups attached to the polymer backbone of the fibers, available forcrosslinking. In one embodiment, the binder fibers comprise athermoplastic polymer having maleic anhydride repeat units grafted ontothe thermoplastic polymer. These anhydride groups are reactive withprotic compounds that contain hydroxyl groups, amine groups, or aromaticrings. A portion of the anhydride groups may be opened with water in theenvironment to give carboxylic acid groups. Preferably, the water basedthermosetting resin is selected such that when the resin is cured, itreacts and covalently bonds with the cellulosic fibers and/or the binderfibers comprise a thermoplastic polymer having maleic anhydride repeatunits graphed onto the thermoplastic polymer. In one embodiment, thethermosetting resin is a blend of: a compound containing two or morecarboxylic acid groups, a compound containing two or more hydroxylgroups, and optionally a catalyst that promotes the condensationreaction between carboxylic and hydroxyl groups. When heat is applied,the carboxylic acid and hydroxyl groups undergo a condensation reactionto form an ester-crosslinked system. The components of the thermosettingresin, and cellulosic fibers are crosslinked together through the esterforming process. Additionally, the anhydride groups of the binder fibers(in one embodiment) can react with the hydroxyl groups of the celluloseand the hydroxyl groups of the thermosetting resin to provide a secondcrosslinking method.

Next, the uncured, wet nonwoven layer is at least partially driedforming the moldable, uncured composite. This drying occurs such thatthe temperature at the inner plane is less than about 130° C., morepreferably less than about 110° C. Keeping the temperature at the innerplane below this temperature is important so as not to cure the resin atthis step. Preferably, the drying of the uncured, wet nonwoven layerresults in removing between about 90 and 95% by weight of the water fromthe water-based thermosetting resin.

Preferably, the drying of the uncured, wet nonwoven layer comprisesusing superheated steam. Steam has a higher heat capacity than air, andis therefore naturally a better heating medium. The problem with steamis that it must remain above a certain temperature, or it will start tocondense back into water. This is problematic in drying, becausemoisture pulled from the material naturally cools the heating medium. Soif saturated steam were to be used, it would quickly condense and rainin the drum, because steam is so close to the temperature at which itcondenses. This problem is avoided by using superheated steam as thedrying medium. Superheated steam also allows for the impregnatedstructural nonwoven to be dried without initiating cross-linking/curingof the resin.

The resin 400 is not shown in FIG. 1 due to the difficulty showing sucha thin coating on the fibers 200, 300. FIG. 2 is an enlargement of asection of the cross-section of FIG. 1 where the coating of the uncured,water-based thermosetting resin 400 can be seen on the fibers 200, 300.The coating may be so thin that in some embodiments, the coating mayonly be present at the fiber crossover locations instead of showing upas a true coating.

After the majority of the water is driven off, the moldable, uncuredcomposite comprises between about 5 and 50% by weight resin, morepreferably between about 5 and 40% by weight resin. After the majorityof the water is driven off, the moldable, uncured composite comprisesbetween about 25 and 40% by weight binder, more preferably between about25 and 40% by weight resin.

This moldable, uncured composite differs from some other thermoset resinand fiber composites where the resin is the continuous component withsome fibers suspended in the resin. In this moldable, uncured compositethe majority of the composite is fibers with the resin forming a coatingon the fibers. Preferably, the resin is not continuous throughout thecomposite.

The moldable, uncured composite 10 is preferably still flexible. Thismeans that the moldable, uncured composite 10 is able to be completelyfolded onto itself (a 180 degree fold) and then can be unfolded withoutany permanent changes in appearance or physical properties. Thisflexibility is important for the composite to be used in certainapplications like in molded parts for cars.

Next, the moldable, uncured nonwoven composite 10 may be cut into adesired shape and size and the cured. To cure the moldable, uncurednonwoven composite 10 into a molded, cured composite, heat andoptionally pressure is applied to the moldable, uncured nonwovencomposite 10 heating the uncured composite to a temperature of at leastabout 160° C. (measured at the inner plane of the structural nonwovenlayer). This melts at least partially melts the binder fibers and curesthe thermosetting resin bonding at least a portion of the reinforcingfibers to other reinforcing fibers. In the cured composite, at least aportion of the binder fibers may still have a fibrous shape with theother fibers melting into binder material (the binder material typicallycoating the reinforcing fibers or forming adhesive blobs).

In the embodiment where the binder fibers are bi-component fabriccontaining a core and sheath, preferably the sheath of the fibers meltswhile the core of the fibers remains (in a fibrous form). Preferably,the sheath polymer and cured thermoset resin bonds at least a portion ofthe reinforcing fibers to other reinforcing fibers, at least a portionof the reinforcing fibers to the core of the bi-component fibers, andleast a portion of the cores of the bi-component fibers to other coresof the bi-component fibers.

The molded, cured nonwoven composite preferably is less flexible thanthe uncured nonwoven composite. Preferably, the molded, cured nonwovencomposite is stiff enough to support its own weight, hold its own shape,and may even be stiff enough to support additional weight withoutchanging its shape. In one embodiment, the molded, cured nonwovencomposite has a maximum flexural lead of at least 28 N.

In one embodiment, the moldable, uncured nonwoven composite 10 (and themolded, cured composite 20) contains additional fibers. The additionalfibers may be uniformly distributed throughout the structural nonwovenlayer 100 or may have a stratified concentration. These additionalfibers may include, but are not limited to additional binder fibershaving a different denier, staple length, composition, or melting point,additional bulking fibers having a different denier, staple length, orcomposition, and an effect fiber, providing benefit a desired aestheticor function. These effect fibers may be used to impart color, chemicalresistance (such as polyphenylene sulfide fibers andpolytetrafluoroethylene fibers), moisture resistance (such aspolytetrafluoroethylene fibers and topically treated polymer fibers), orothers.

In one embodiment, the additional fibers may be heat and flame resistantfibers, which are defined as fibers having a Limiting Oxygen Index (LOl)value of 20.95 or greater, as determined by ISO 4589-1. Examples of heatand flame resistant fibers include, but are not limited to thefollowing: fibers including oxidized polyacrylonitrile, aramid, orpolyimid, flame resistant treated fibers, FR rayon, carbon fibers, orthe like. These heat and flame resistant fibers may also act as thebulking fibers or may be used in addition to the bulking fibers.

All of the fibers within the moldable, uncured nonwoven composite 10(and the molded, cured composite 20) may optionally contain additives.Suitable additives include, but are not limited to, fillers,stabilizers, plasticizers, tackifiers, flow control agents, cure rateretarders, adhesion promoters (for example, silanes and titanates),adjuvants, impact modifiers, expandable microspheres, thermallyconductive particles, electrically conductive particles, silica, glass,clay, talc, pigments, colorants, glass beads or bubbles, antioxidants,optical brighteners, antimicrobial agents, surfactants, fire retardants,and fluoropolymers. One or more of the above-described additives may beused to reduce the weight and/or cost of the resulting fiber and layer,adjust viscosity, or modify the thermal properties of the fiber orconfer a range of physical properties derived from the physical propertyactivity of the additive including electrical, optical, density-related,liquid barrier or adhesive tack related properties.

In one embodiment, the moldable, uncured nonwoven composite 10 (and themolded, cured composite 20) may contain an additional nonwoven layer.The additional nonwoven layer may be exactly same as the structuralnonwoven layer 100 or may have different fibers, densities, and ratios.The properties described in relation to the structural nonwoven layer100 are applicable to the additional nonwoven layer. The additionalnonwoven layer(s) may be attached to one or both sides of the structuralnonwoven layer 100 by any suitable means such as needling or adhesives.

Referring now to FIG. 3, there is shown another embodiment where themoldable, uncured nonwoven composite 10 contains the structural layer100 (as described above) and an outermost layer 800. The outermostnonwoven layer 800 has an outer surface 800 a and an inner surface 800b. The outermost nonwoven layer and the structural nonwoven layer areplaced together such that the outer surface 800 a of the outermostnonwoven layer 800 forms the first side 10 a of the composite 10 and thesecond surface 100 b of the structural layer 100 forms the second side10 b of the composite 10. The inner surface 800 b of the outermostnonwoven layer 800 is next to and adjacent the first surface 100 a ofthe structural nonwoven layer 100. The two nonwoven layers 100, 800 maybe in direct contain (they would be in intimate contact with no othermaterial between them) or there may be additional material between thetwo layers (such as an adhesive, a film, an additional nonwoven, or awoven or knit fabric).

The outermost nonwoven layer 800 contains a plurality of first fiberswhich have a melting temperature greater than 130° C. The A surfacelayer can comprise a nonwoven, knit or a woven product. In a preferredembodiment, the A surface comprises a needlepunch nonwoven layer. Thenonwoven contains PET or PP staple fibers that are color matched to anOEM (original equipment manufacturer) specified master. The typicalweights of the nonwoven layer are between 150 gsm and 400 gsm. Thetypical thickness of the A layer is between 500 microns and 1.5 mm.

The A surface layer can comprise a nonwoven, knit or a woven product. Inthe preferred embodiment, the A surface comprises a needlepunch nonwovenlayer. The nonwoven contains PET or PP staple fibers that are colormatched to an OEM specified master. The typical weights of the nonwovenlayer are between 150 gsm and 400 gsm. The typical thickness of the Alayer is between 500 microns and 1.5 mm. In one embodiment, theoutermost nonwoven layer 800 may contain a plurality of binder fibers(which may be the same or different binder fibers than in the structuralnonwoven layer 100), or other binder material.

The structural nonwoven layer 100 and the outermost nonwoven layer 800are needled together from both the outer surface of the outermostnonwoven layer and the second surface of the structural nonwoven layer,wherein the needling causes a portion of the first fibers from theoutermost nonwoven layer to migrate into the structural nonwoven layerand causes a portion of the structural fibers and the binder fibers fromthe structural nonwoven layer to migrate into the outermost nonwovenlayer.

When the uncured, water-based thermosetting resin having a curetemperature of at least about 160° C. is applied to the embodiment ofthe composite 10 shown in FIG. 3, the resin is applied to the secondsurface 100 b of the structural nonwoven layer 100, partiallyimpregnating the nonwoven layers 100, 800 forming an uncured, wetnonwoven composite, wherein at least 90% by weight of the water-basedthermosetting resin is located in the structural nonwoven layer 100.Preferably, at least 95% by weight of the water-based thermosettingresin is located in the structural nonwoven layer 100. In anotherembodiment, essentially no (less than 1% by weight) of the thermosettingresin is on the outermost surface 800 a of the outermost nonwoven layer800.

The layered composite is impregnated from the bottom side with thethermosetting resin. Preferred impregnation equipment is a parabolicfoam coater or a rotary screen coater. The penetration of the resinstops at the interface of the structural and aesthetic layers. This canbe controlled with the process and/or the structure of the layeredcomposite. When controlled with the process, the applicator pressure andresin concentration must control the penetration of the resin so that itdoes not penetrate too far into the A-substrate. If it penetrates toofar, the touch, feel, and appearance of the A-surface suffers.

Additionally, a “penetration stop layer” can be built into thesubstrate. Some example layers include a film, spunbond nonwoven, or acoating of cationic-containing polymer applied to the interface beforeneedlepunching them together, capable of coagulating anionicallystabilized thermosetting resin latex. With these layers, the latexsaturates the structural layer but stops penetration at the interface,leaving the face layer with a natural feel and look.

While it is theoretically possible to impregnate the structural nonwovenand then needle-in the face layer, there are process challenges thatwould cause a) greater needle breakage as a result of the stiffness ofthe impregnated structural layer and 2) distorting the appearance of theface layer during the composite step.

The cured or uncured composite may also contain any additional layersfor physical or aesthetic purposes. Suitable additional layers include,but are not limited to, a non-woven fabric, a woven fabric, a knittedfabric, a foam layer, a film, a paper layer, an adhesive-backed layer, afoil, a mesh, an elastic fabric (i.e., any of the above-described woven,knitted or non-woven fabrics having elastic properties), an aperturedweb, an adhesive-backed layer, or any combination thereof. Othersuitable additional layers include, but are not limited to, acolor-containing layer (e.g., a print layer); one or more additionalsub-micron fiber layers having a distinct average fiber diameter and/orphysical composition; one or more secondary fine fiber layers foradditional insulation performance (such as a melt-blown web or afiberglass fabric); foams; layers of particles; foil layers; films;decorative fabric layers; membranes (i.e., films with controlledpermeability, such as dialysis membranes, reverse osmosis membranes,etc.); netting; mesh; wiring and tubing networks (i.e., layers of wiresfor conveying electricity or groups of tubes/pipes for conveying variousfluids, such as wiring networks for heating blankets, and tubingnetworks for coolant flow through cooling blankets); or a combinationthereof. The additional layers may be on either or both sides of thenon-woven composite. For example, a textile may be applied to one sideof the non-woven composite using an optional adhesive layer to form anaesthetic surface for an end use such as certain automobileapplications.

The cured or uncured composite may further comprise one or moreattachment devices to enable the composite to be attached to a substrateor other surface. In addition to adhesives, other attachment devices maybe used such as mechanical fasteners like screws, nails, clips, staples,stitching, thread, hook and loop materials, etc.

The one or more attachment devices may be used to attach the compositeto a variety of substrates. Exemplary substrates include, but are notlimited to, a vehicle component; an interior of a vehicle (i.e., thepassenger compartment, the motor compartment, the trunk, etc.); a wallof a building (i.e., interior wall surface or exterior wall surface); aceiling of a building (i.e., interior ceiling surface or exteriorceiling surface); a building material for forming a wall or ceiling of abuilding (e.g., a ceiling tile, wood component, gypsum board, etc.); aroom partition; a metal sheet; a glass substrate; a door; a window; amachinery component; an appliance component (i.e., interior appliancesurface or exterior appliance surface); a surface of a pipe or hose; acomputer or electronic component; a sound recording or reproductiondevice; a housing or case for an appliance, computer, etc.

EXAMPLES

The invention will now be described with reference to the followingnon-limiting examples, in which all parts and percentages are by weightunless otherwise indicated.

Example 1

Example 1 was a structural non-woven fiber based composite comprising afirst side and a second side. The non-woven layer was formed from ablend of two fibers and had a basis weight of 700 gram/m²:

-   -   1) 20% by weight of a 4 denier polyester core-180 C co-polyester        sheath fiber.    -   2) 80% by weight of a triple-carded kenaf (bast) fiber which had        a linear density of approximately 8.8-2 dtex (8-18 denier)

The structural nonwoven layer was produced using a standard industrialscale needle punch carpet production line. Staple fibers as indicatedabove were mixed and formed in a mat using carding and cross-lapping.The mat was pre-needled using plain barbed needles to form the non-wovenlayers. The structural nonwoven layer was impregnated with ACRODUR™DS3515 using a Gaston county parabolic foam coater. The impregnatednonwoven composite was dried in a RF oven until the residual moisturelevel is 15%. The dry add-on weight of the ACRODUR™ resin was 42% (294gsm) of the structural nonwoven layer.

Example 2

Example 1 was consolidated using a heated platen press, with the platentemperatures set at 400° F. to melt the low-melt binder fibers andcross-link the ACRODUR™ DS3515 resin. The cycle time was 45 seconds andthe consolidated non-woven composite had a thickness of 2.5 mm. Theapplication of heat and pressure allows the low-melt binder fiber andACRODUR™ resin to bond the reinforcing fibers together.

Example 3

Example 3 was a structural non-woven fiber based composite comprising afirst side and a second side. The non-woven layer was formed from ablend of two fibers and had a basis weight of 700 gram/m²:

-   -   1) 50% by weight of a 8 denier PP fiber that had been grafted        with approximately 10 wt. % maleic anhydride (MAH).    -   2) 50% by weight of a triple-carded kenaf (bast) fiber which had        a linear density of approximately 8.8-2 dtex (8-18 denier)

The structural nonwoven layer was produced using a standard industrialscale needle punch carpet production line. Staple fibers as indicatedabove were mixed and formed in a mat using carding and cross-lapping.The mat was pre-needled using plain barbed needles to form the non-wovenlayers. The structural nonwoven layer was impregnated with ACRODUR™DS3515 using a Gaston county parabolic foam coater. The impregnatednonwoven composite was dried in a RF oven until the residual moisturelevel is 15%. The dry add-on weight of the ACRODUR™ resin was 42% (294gsm) of the structural nonwoven layer.

Example 4

Example 3 was consolidated using a heated platen press, with the platentemperatures set at 400° F. to melt the low-melt binder fibers andcross-link the ACRODUR™ DS3515 resin. The cycle time was 45 seconds andthe consolidated non-woven composite had a thickness of 2.5 mm. Theapplication of heat and pressure allows the PP binder fiber and ACRODUR™resin to bond the reinforcing fibers together. The MAH groups on the PPfiber covalently bond to the hydroxyl groups on the kenaf fibers and theACRODUR™ resin.

Example 5

Example 5 was a structural non-woven fiber based composite comprising afirst zone and a second zone. The non-woven layer forming the first zonewas formed from a blend of two fibers and had a basis weight of 150gram/m²:

-   -   1) 95% by weight of a 6 denier PET staple fiber.    -   2) 5% by weight of a 4 denier (4.4 decitex) low melt binder        fiber. The fiber is a core-sheath polyester fiber with a lower        melting temperature sheath.

The non-woven layer was formed from a blend of two fibers and had abasis weight of 700 gram/m²:

-   -   1) 20% by weight of a 4 denier polyester core-180 C co-polyester        sheath fiber.    -   2) 80% by weight of a triple-carded kenaf (bast) fiber which had        a linear density of approximately 8.8-2 dtex (8-18 denier)

The non-woven layers forming the zones were produced using a standardindustrial scale needle punch carpet production line. Staple fibers asindicated above were mixed and formed in a mat using carding andcross-lapping. The mat was pre-needled using plain barbed needles toform the non-woven layers. The first zone (first non-woven) and secondzone (second non-woven) were then needled together using a needle-loomfrom the first zone side of the non-woven. The needling pushed fibersfrom the first zone into the second zone and essentially no fibers fromthe second zone were in the first zone. The structural nonwoven layerwas impregnated with ACRODUR™ DS3515 using a Gaston county parabolicfoam coater. The pressure and concentration of the resin was tuned tolimit the depth of penetration of the resin. The impregnated nonwovencomposite was dried at a temperature of 90 C in a convection tenter ovenuntil the residual moisture level is 15%. The dry add-on weight of theACRODUR™ resin was 35% (245 gsm) of the structural nonwoven layer.

Example 6

Example 5 was consolidated using a heated platen press, with the platentemperatures set at 400° F. to melt the low-melt binder fibers andcross-link the ACRODUR™ DS3515 resin. The cycle time was 45 seconds andthe consolidated non-woven composite had a thickness of 3.2 mm. Theapplication of heat and pressure allows the low-melt binder fiber andACRODUR™ resin to bond the reinforcing fibers together.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the subject matter of this application (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The terms “comprising,” “having,”“including,” and “containing” are to be construed as open-ended terms(i.e., meaning “including, but not limited to,”) unless otherwise noted.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the subject matter of theapplication and does not pose a limitation on the scope of the subjectmatter unless otherwise claimed. No language in the specification shouldbe construed as indicating any non-claimed element as essential to thepractice of the subject matter described herein.

Preferred embodiments of the subject matter of this application aredescribed herein, including the best mode known to the inventors forcarrying out the claimed subject matter. Variations of those preferredembodiments may become apparent to those of ordinary skill in the artupon reading the foregoing description. The inventors expect skilledartisans to employ such variations as appropriate, and the inventorsintend for the subject matter described herein to be practiced otherwisethan as specifically described herein. Accordingly, this disclosureincludes all modifications and equivalents of the subject matter recitedin the claims appended hereto as permitted by applicable law. Moreover,any combination of the above-described elements in all possiblevariations thereof is encompassed by the present disclosure unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A process for forming a moldable, uncurednonwoven composite having a first side and a second side comprising:forming a outermost nonwoven layer having an outer surface and an innersurface, wherein the outermost nonwoven layer comprises a plurality offirst fibers, wherein the first fibers have a melting temperaturegreater than about 130° C.; forming a structural nonwoven layer having afirst surface, a second surface, and an inner plane located at themid-plane between the first and second surface, wherein the structuralnonwoven layer comprises a plurality of binder fibers and a plurality ofreinforcing fibers; placing the structural nonwoven layer and theoutermost nonwoven layer together such that the inner surface of theoutermost nonwoven layer is adjacent the first surface of the structuralnonwoven layer and the outer surface of the outermost nonwoven layerforms the first side of the moldable, uncured nonwoven composite;needling the structural nonwoven layer and the outermost nonwoven layertogether from both the outer surface of the outermost nonwoven layer andthe second surface of the structural nonwoven layer, wherein theneedling causes a portion of the first fibers from the outermostnonwoven layer to migrate into the structural nonwoven layer and causesa portion of the structural fibers and the binder fibers from thestructural nonwoven layer to migrate into the outermost nonwoven layer;applying an uncured, water-based thermosetting resin having a curetemperature of at least about 160° C. to the second surface of thestructural nonwoven layer, partially impregnating the nonwoven layersforming an uncured, wet nonwoven composite, wherein at least 90% byweight of the water-based thermosetting resin is located in thestructural nonwoven layer; and, at least partially drying the uncured,wet nonwoven composite such that the temperature at the inner plane ofthe structural nonwoven layer is less than about 160° C. forming anmoldable, uncured nonwoven composite.
 2. The process of claim 1, whereinthe outermost nonwoven layer further comprises a plurality of binderfibers.
 3. The process of claim 1, wherein the binder fibers in thestructural nonwoven layer are bi-component fibers comprising a core anda sheath, wherein the core comprises a polymer having a meltingtemperature of at least about 190° C. and the sheath comprises a polymerhaving a melting temperature less than about 190° C.
 4. The process ofclaim 1, further comprising placing an adhesive between the innersurface of the outermost nonwoven layer and first surface of thestructural nonwoven layer before or during the step of placing thestructural nonwoven layer and the outermost nonwoven layer together. 5.The process of claim 1, wherein drying the uncured, wet nonwovencomposite comprises removing between 90 and 95% of the water.
 6. Theprocess of claim 1, wherein the binder material and the water-basedthermosetting resin comprise polyester.
 7. A moldable, uncured nonwovencomposite formed by the process of claim
 1. 8. A process for forming amolded, cured nonwoven composite having a first side and a second sidecomprising: forming a outermost nonwoven layer having an outer surfaceand an inner surface, wherein the outermost nonwoven layer comprises aplurality of first fibers, wherein the first fibers have a meltingtemperature greater than about 130° C.; forming a structural nonwovenlayer having a first surface, a second surface, and an inner planelocated at the mid-plane between the first and second side, wherein thestructural nonwoven layer comprises a plurality of binder fibers and aplurality of reinforcing fibers; placing the structural nonwoven layerand the outermost nonwoven layer together such that the inner surface ofthe outermost nonwoven layer is adjacent the first surface of thestructural nonwoven layer and the outer surface of the outermostnonwoven layer forms the first side of the moldable, uncured nonwovencomposite; needling the structural nonwoven layer and the outermostnonwoven layer together from both the outer surface of the outermostnonwoven layer and the second surface of the structural nonwoven layer,wherein the needling causes a portion of the first fibers from theoutermost nonwoven layer to migrate into the structural nonwoven layerand causes a portion of the structural fibers and the binder fibers fromthe structural nonwoven layer to migrate into the outermost nonwovenlayer; applying an uncured, water-based thermosetting resin having acure temperature of at least about 160° C. to the second surface of thestructural nonwoven layer, partially impregnating the nonwoven layersforming an uncured, wet nonwoven composite, wherein at least 90% byweight of the water-based thermosetting resin is located in thestructural nonwoven layer; at least partially drying the uncured, wetnonwoven composite such that the temperature at the inner plane of thestructural nonwoven layer is less than about 160° C. forming anmoldable, uncured nonwoven composite; cutting the moldable, uncurednonwoven composite; and, applying heat and pressure to the moldable,uncured nonwoven composite to a temperature of at least about 160° C. atleast partially melting the binder fibers and bonding at least a portionof the reinforcing fibers together and at least partially curing thethermosetting resin forming the molded, cured nonwoven composite.
 9. Theprocess of claim 8, wherein the binder fibers in the structural nonwovenlayer are bi-component fibers comprising a core and a sheath, whereinthe core comprises a polymer having a melting temperature of at leastabout 160° C. and the sheath comprises a polymer having a meltingtemperature less than about 160° C.
 10. The process of claim 8, furthercomprising placing an adhesive between the inner surface of theoutermost nonwoven layer and first surface of the structural nonwovenlayer before or during the step of placing the structural nonwoven layerand the outermost nonwoven layer together.
 11. The process of claim 8,wherein drying the uncured, wet nonwoven composite comprises removingbetween 90 and 95% of the water.
 12. The process of claim 8, wherein thebinder material and the water-based thermosetting resin comprisepolyester.
 13. A molded, cured nonwoven composite formed by the processof claim 8.